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NASA’s newest sun-watcher, the Interface Region Imaging Spectrograph, launched in 2013 with a specific goal: track how energy and heat coursed through a little understood region of the sun called the interface region. Sandwiched between the solar surface and its outer atmosphere, the corona, the interface region is where the cooler temperatures of the sun’s surface transition to the hotter temperatures above. Moreover, all the energy to power the sun’s output — including eruptions such as solar flares and the sun’s constant outflow of particles called the solar wind — must make its way through this region.

Five papers based on IRIS data will highlight different aspects of the energy’s journey from the sun’s surface through its atmosphere in the Oct. 17, 2014, issue of Science magazine. By looking at various regions of the interface region in unprecedented resolution, the papers offer clues to what heats the corona to unexplained temperatures of millions of degrees, far hotter than the surface of the sun itself, as well as what causes great writhing movement and accelerated particles throughout the solar atmosphere.

“This set of research really delivers on the promise of IRIS, which has been looking at a region of the sun with a level of detail that has never been done before,” said Bart De Pontieu the IRIS science lead at Lockheed Martin in Palo Alto, California. “The results focus on a lot of things that have been puzzling for a long time and they also offer some complete surprises.”

Solar Heat Bombs

One of the biggest surprises comes in the form of heat pockets of 200,000 F, low in the solar atmosphere – far lower down than where such high temperatures were expected. In a paper led by Hardi Peter of the Max Planck Institute for Solar System Research in Gottingen, Germany, the pockets were named bombs because of how much energy they release in such a short time.

Bright lights in this movie from NASA’s IRIS, represents spots of intense heat — at 200,000 F — that may hold clues to what heats the solar atmosphere to mysteriously high temperatures.
Image Credit: NASA/IRIS/Peter

Identifying different temperature material in the solar atmosphere is fairly straightforward, but it is much more complex to determine how high above the surface such material lies. Spotting such features relied heavily on IRIS’ high-resolution spectrograph, an instrument that divides incoming light into its separate wavelengths. Such spectra can then be analyzed to see what temperature material is present in a given area as well as how dense it is and how fast it is moving. IRIS showed this very hot material sandwiched between two cold layers at temperatures usually found only near the sun’s surface, thus giving information about its low-lying location that would have been otherwise hard to find…. Continue reading NASA’s IRIS Helps Explain Mysterious Heating of the Solar Atmosphere→

A coronal mass ejection burst off the side of the sun on May 9, 2014. The giant sheet of solar material erupting was the first CME seen by NASA’s Interface Region Imaging Spectrograph, or IRIS. The field of view seen here is about five Earth’s wide and about seven and a half Earth’s tall.

IRIS must commit to pointing at certain areas of the sun at least a day in advance, so catching a CME in the act involves some educated guesses and a little bit of luck.

These two images show a section of the sun as seen by NASA’s Interface Region Imaging Spectrograph, or IRIS, on the right and NASA’s SDO on the left. The IRIS image provides scientists with unprecedented detail of the lowest parts of the sun’s atmosphere, known as the interface region.Image Credit: NASA/SDO/IRIS

The moment when a telescope first opens its doors represents the culmination of years of work and planning — while simultaneously laying the groundwork for a wealth of research and answers yet to come. It is a moment of excitement and perhaps even a little uncertainty. On July 17, 2013, the international team of scientists and engineers who supported and built NASA’s Interface Region Imaging Spectrograph, or IRIS, all lived through that moment. As the spacecraft orbited around Earth, the door of the telescope opened to view the mysterious lowest layers of the sun’s atmosphere and the results thus far are nothing short of amazing. The data is crisp and clear, showing unprecedented detail of this little-observed region.
“These beautiful images from IRIS are going to help us understand how the sun’s lower atmosphere might power a host of events around the sun,” said Adrian Daw, the mission scientist for IRIS at NASA’s Goddard Space Flight Center in Greenbelt, Md. “Anytime you look at something in more detail than has ever been seen before, it opens up new doors to understanding. There’s always that potential element of surprise.”
As the telescope door opened on July 17, 2013, IRIS’s single instrument began to observe the sun in exceptional detail. IRIS’s first images showed a multitude of thin, fibril-like structures that have never been seen before, revealing enormous contrasts in density and temperature occur throughout this region even between neighboring loops that are only a few hundred miles apart. The images also show spots that rapidly brighten and dim, which provide clues to how energy is transported and absorbed throughout the region.
The IRIS images of fine structure in the interface region will help scientists track how magnetic energy contributes to heating in the sun’s atmosphere. Scientists need to observe the region in exquisite detail, because the energy flowing through it powers the upper layer of the sun’s atmosphere, the corona, to temperatures greater than 1 million kelvins (about 1.8 million F), almost a thousand times hotter than the sun’s surface itself.
IRIS is a NASA Small Explorer mission that launched from Vandenberg Air Force Base, Calif., on June 27, 2013. IRIS’s capabilities are uniquely tailored to unravel the interface region. Understanding the interface region is important because it forms the ultraviolet emission that impacts near-Earth space and Earth’s climate. Energy traveling through the region also helps drive the solar wind, which during extreme space weather events near Earth can affect satellites, power grids, and global positioning systems, or GPS.
Designed to research the interface region in more detail than has ever been done before, IRIS’s instrument is a combination of an ultraviolet telescope and what’s called a spectrograph. Light from the telescope is split into two components. The first provides high-resolution images, capturing data on about one percent of the sun at a time. While these are relatively small snapshots, the images can resolve very fine features, as small as 150 miles across.
While the images are of one wavelength of light at a time, the second component is the spectrograph that provides information about many wavelengths of light at once. The instrument splits the sun’s light into its various wavelengths and measures how much of any given wavelength is present. This information is then portrayed on a graph showing spectral “lines.” Taller lines correspond to wavelengths in which the sun emits relatively more light. Analysis of the spectral lines can also provide velocity, temperature and density, key information when trying to track how energy and heat moves through the region.
“The quality of images and spectra we are receiving from IRIS is amazing. This is just what we were hoping for,” said Alan Title, IRIS principal investigator at the Lockheed Martin Advanced Technology Center Solar and Astrophysics Laboratory in Palo Alto, Calif. “There is much work ahead to understand what we’re seeing, but the quality of the data will enable us to do that.”
Not only does IRIS provide state-of-the-art observations to look at the interface region, it makes uses of advanced computing to help interpret what it sees. Indeed, interpreting the light flowing out of the interface region could not be done well prior to the advent of today’s supercomputers because, in this area of the sun, the transfer and conversion of energy from one form to another is not understood.
The IRIS mission has long-term implications for understanding the genesis of space weather near Earth. Understanding how energy and solar material move through the interface region could help scientists improve forecasts for the kinds of events that can disrupt Earth technologies.
Read more at www.nasa.gov

Engineers work with the IRIS spacecraft on the nose of the Pegasus XL rocket that will launch the solar observatory into Earth orbit. Photo credit: VAFB/Rnady Beaudoin

By Steven Siceloff,
NASA’s Kennedy Space Center

Researchers hope NASA’s latest solar observatory will answer a fundamental question of how the sun creates such intense energy.

Scheduled to launch June 27, the IRIS spacecraft will point a telescope at the interface region of the sun that lies between the surface and the million degree outer atmosphere called the corona. It will improve our understanding of how energy moves from the sun’s surface to the glowing corona, heating up from 6,000 degrees to millions of degrees.

The IRIS mission, short for Interface Region Imaging Spectrograph, calls for the 7-foot-long spacecraft to point its ultraviolet telescope at the sun to discern features as small as 150 miles across. It will look at about 1 percent of the sun’s surface.

“IRIS will show the solar chromosphere in more detail than has ever been observed before,” said Adrian Daw, deputy project scientist. “My opinion is that we are bound to see something we didn’t expect to see.”

IRIS is a NASA Small Explorer that will complement the Solar Dynamics Observatory and Hinode missions to explore how the solar atmosphere works and impacts Earth. SDO and Hinode will monitor the solar surface and outer atmosphere, with IRIS watching the region in between.

“IRIS almost acts as a microscope to SDO’s telescope,” said Jim Hall, mission manager for IRIS. “It’s going to look in closely and it’s going to look at that specific region to see how the changes in matter and energy occur in this region. It’s going to collectively bring us a more complete view of the sun.” IRIS improves our understanding of the interface region where most of the sun’s ultraviolet emission is generated that impacts the near Earth space environment and Earth’s climate. Solar activity such as coronal mass ejections and solar flares, also are of great interest to spacecraft designers who have to figure out ways to protect instruments and electronics from them.

“We’re always looking for the answers to why and everything starts at the root with the sun,” Hall said.

IRIS will ride into Earth orbit on an Orbital Sciences Pegasus XL rocket. The Pegasus is famous as the only winged launcher in NASA’s inventory. Though small compared to the gigantic boosters that send heavy satellites into orbit and probes to distant worlds, the Pegasus’ size and flexibility has allowed numerous missions to be launched that would have been too small for larger rockets.

“Pegasus has been a tremendously successful launch vehicle for NASA,” said Tim Dunn, launch director for IRIS. “We have launched 18 successful missions on Pegasus. The team is very dynamic, very flexible. They’re able to accomplish a tremendous amount in a very short time.”

The Pegasus and its IRIS payload will be carried to about 39,000 feet under a modified L-1011 airliner taking off from Vandenberg Air Force Base in California. Over the Pacific Ocean off the California coast, the plane will drop the Pegasus to begin the launch.

The Pegasus will ignite its solid-fueled first stage five seconds into its fall and arch skyward with the main wing giving it lift and the three fins in the back steering it through the thick layers of Earth’s lower atmosphere.

The rocket will burn its load of fuel in 73 seconds and fall away. The second stage, which has no wings, will ignite 94 seconds into flight and push IRIS higher and faster into space. The third stage will take over after that, delivering IRIS into its orbit about 10 minutes after launch.

This is the last one scheduled for the Pegasus rocket because there are not any small spacecraft missions that fit the Pegasus niche.

The launch is taking place from the West Coast because IRIS will go into a roughly polar orbit, meaning it will cross over the north and south pole regions of Earth on each pass around the planet.

“Eight months out of the year, we are freely viewing the sun in that orbit,” Hall said.

Once IRIS is in space with its solar panels unfolded to provide electricity and the telescope flipped open, scientists expect to see intriguing data pretty quickly.